Application Security Testing (AST): Types, Uses, and How It Works

What is Application Security Testing?

Application Security Testing is the practice of checking software for security issues. It helps find and fix weaknesses in applications, so hackers cannot exploit them. It involves both automated tools and manual techniques to detect vulnerabilities such as insecure code, misconfigurations, broken authentication, and exposed APIs. The goal of security testing is to ensure the confidentiality, integrity, and availability of application data by detecting and fixing security vulnerabilities that could expose sensitive information or disrupt services.

AST helps teams reduce risk, stay compliant, and build secure software that customers and stakeholders can trust.

Why is Application Security Testing Critical?

1. Applications Are the New Perimeter

In modern cloud-native, microservices, API-first, and SaaS architectures, applications expose the business directly to the internet, bypassing traditional network boundaries. Firewalls and VPNs no longer provide sufficient protection because attackers target the application layer, where they can exploit:

• Business logic vulnerabilities (e.g., bypassing payment flows or manipulating discounts)
• Injection vulnerabilities (SQL, command, or LDAP injections)
• Misconfigured APIs leaking sensitive data
• Broken authentication or session management
• Client-side attacks like magecart or formjacking

Since applications handle sensitive data and transactions, they are prime targets for cybercriminals. Failing to secure them can lead to breaches, data loss, and brand damage.

2. Compliance Requires It

Security testing is strongly recommended by nearly every major regulatory or security standard, often with detailed requirements around application-level assessments:

• PCI DSS 4.0 – Requirements 6.3.2 and 11.3 mandate vulnerability scanning and penetration testing of applications that process or store cardholder data.
• HIPAA Security Rule – Requires covered entities and business associates to conduct regular risk assessments of applications that store, or process protected health information (PHI).
• GDPR Article 32 – Under GDPR Article 32, organizations must implement ongoing processes to test, assess, and review the effectiveness of technical and organizational safeguards protecting the security of personal data processing, particularly in applications involving EU residents’ information.
• ISO/IEC 27001:2022 – Control A.14.2 (Security in Development and Support Processes) specifically requires security testing during application development and after major changes.
• SOC 2 (Trust Services Criteria) – The Security and Confidentiality principles expect security controls, including vulnerability management for in-scope applications.
• NIST frameworks (e.g., NIST 800-53 SA-11) – Recommend application-level security testing as part of a comprehensive security assessment program.

Failing to meet these requirements can lead to non-compliance penalties, regulatory fines, lawsuits, and erosion of customer trust.

Learn more about how application security drives compliance and helps you meet industry-specific regulations effectively.

3. Catching Vulnerabilities Early Saves Costs

Fixing a security issue in production can cost 30 times more than catching it during development. AST integrated early in the software development lifecycle (SDLC) helps identify and remediate vulnerabilities before code is deployed, avoiding costly rework, emergency patches, and potential downtime.

Early detection also reduces the window of exposure, minimizing the chance of exploitation in production.

4. Enables DevSecOps and Agile Security

Modern development practices rely on fast, iterative releases through Agile and DevOps. Without AST, security assessments become bottlenecks, leading to either:

• Delayed releases while waiting for manual security checks, or
• Shipping insecure code to production, increasing breach risk.

Integrating AST into CI/CD pipelines, a key aspect of DevSecOps allows:

• Automated scans to catch vulnerabilities every time code is committed or deployed
• Continuous feedback loops for developers to fix vulnerabilities promptly
• Maintaining security at the speed of innovation, ensuring that rapid feature delivery doesn’t compromise safety or compliance

This “shift-left” approach brings security closer to the developers, embedding it as a shared responsibility across the team rather than an afterthought.

Who Should Invest in Application Security Testing?

Organizations that develop, manage, or integrate software applications need to implement AST. This includes:

• SaaS companies and product development teams
• Enterprises with customer portals or internal applications
• E-commerce platforms handling PII and payment data
• Healthcare, fintech, and insurance platforms
• Government and defense systems
• Startups planning for security-by-design maturity

Even organizations using third-party vendors must validate the security of integrated applications, APIs, and microservices.

Types of Application Security Testing

Each type of testing serves a unique purpose across the software lifecycle. Mature AST programs often combine multiple methods for layered protection.

1. Static Application Security Testing (SAST)

• What it Does: Analyzes source code, bytecode, or binaries without executing the application.
• Goal: Identify vulnerabilities like unsafe functions, hardcoded secrets, and insecure logic early in development.
• Integration: IDE plugins, build pipelines.
• Strengths: Early feedback; language-specific insight.
• Limitations: False positives and limited runtime context.

2. Dynamic Application Security Testing (DAST)

• What it Does: Scans running applications from the outside, simulating how attackers might exploit exposed functionality.
• Goal: Identify runtime vulnerabilities like authentication flaws, XSS, CSRF, insecure cookies, and misconfigurations.
• Integration: QA, staging, production testing.
• Strengths: No access to source code needed; language-agnostic.
• Limitations: Limited visibility into internal logic or back-end APIs.

However, Indusface WAS overcomes this limitation by combining automated DAST with manual expert evaluation, where security analysts actively test applications for business logic vulnerabilities, complex workflows, and vulnerabilities that automated tools alone can miss. This hybrid approach ensures deeper coverage of application behavior, helping organizations identify and remediate logic-based attacks that standard DAST scans often overlook.

3. Interactive Application Security Testing (IAST)

• What it Does: Instruments the application to monitor real-time behavior during runtime. Blends benefits of SAST and DAST.
• Goal: Provide in-depth, context-aware vulnerability detection with fewer false positives.
• Integration: QA and CI/CD pipelines during functional testing.
• Strengths: Real-time, low noise, detailed tracing.
• Limitations: Requires integration and test traffic.

4. Software Composition Analysis (SCA)

What it Does: Scans application codebases for third-party and open-source components, identifying known vulnerabilities, outdated libraries, and license compliance issues.

Goal: Detect and manage security risks from open-source dependencies, including known CVEs and incompatible or risky licenses.

Integration: Early in development, build pipelines, or during code commits to catch vulnerable components before deployment.

Strengths: Fast scans, visibility into supply chain risks, ensures license compliance.

Limitations: Does not detect custom code vulnerabilities; effectiveness depends on the accuracy of vulnerability databases.

5. Manual Security Testing

• What it Does: Involves human experts performing threat modeling, business logic analysis, and penetration testing.

• Goal: Discover complex vulnerabilities like privilege escalation, chained attacks and business logic vulnerabilities.

• When to Use: Pre-release audits, compliance audits, high-risk applications.
• Strengths: Uncovers what tools cannot.
• Limitations: Cost and time; non-continuous unless scheduled.

Key Differences: SAST vs DAST vs IAST

Feature	SAST	DAST	IAST	SCA
Requires Running App	No	Yes	Yes	No
Access to Source Code	Yes	No	Optional	Yes
Runtime Context	No	Yes (external)	Yes (internal)	No
False Positives	High	Moderate	Low	Low (Known CVEs)
Language Dependency	Language-specific	Language-agnostic	Runtime-dependent	Language-agnostic
CI/CD Friendly	Yes	Somewhat	Yes

Application Vulnerability Assessment vs Penetration Testing

A Vulnerability Assessment is a systematic process of scanning an application to identify, classify, and report known security vulnerabilities. It is typically automated or semi-automated, focusing on breadth rather than depth. The goal is to create an inventory of weaknesses, misconfigurations, or outdated components that attackers could exploit.

Key characteristics:

• Broad, automated scans to find as many potential vulnerabilities as possible.
• Prioritizes vulnerabilities not just by standard scores like CVSS, but Indusface WAS goes further by assessing exploitability, business logic context, and potential business impact, ensuring critical vulnerabilities are highlighted first.
• Provides a comprehensive list of detected vulnerabilities but does not attempt to exploit them, focusing on safe identification.
• Cost-effective and fast, making it ideal for maintaining regular security hygiene and meeting compliance requirements.

Penetration Testing (Pen Testing) goes beyond scanning, it simulates real-world attacks by manually exploiting vulnerabilities to determine their actual impact. It is performed by skilled security professionals who use creative techniques to identify weaknesses missed by automated tools.

Key characteristics:

• Focused, in-depth testing targeting specific high-risk areas.
• Verifies if vulnerabilities are truly exploitable and demonstrates potential consequences.
• Includes exploitation of complex vulnerabilities like business logic vulnerabilities, chained vulnerabilities, or privilege escalation paths.
• Often required for compliance (e.g., PCI DSS) and critical applications.

Aspect	Vulnerability Assessment	Penetration Testing
Purpose	Identify and list vulnerabilities	Exploit vulnerabilities to assess impact
Approach	Broad, automated or semi-automated	Manual, focused, attacker-like approach
Depth	Shallow but wide	Deep but narrow
Validation	Does not confirm exploitability	Confirms and demonstrates real-world risks
Use Case	Regular security hygiene, compliance checks	High-risk apps, mergers & acquisitions, regulatory requirements
Frequency	Frequent (monthly, quarterly, or continuous)	Periodic (e.g., annually or after major changes)

How Does Application Security Testing Work?

Application Security Testing (AST) is not a one-time task it is a continuous process integrated across the entire Software Development Lifecycle (SDLC). By embedding security testing at every phase, organizations can proactively identify and remediate vulnerabilities, reducing the risk of breaches and ensuring compliance.

Here is a detailed look at how AST fits into each SDLC stage:

Design Phase: Threat Modeling

• Before any code is written, teams assess the planned features, architecture, data flows, and interactions with users and third-party systems.
• By conducting threat modeling, they map out how information moves through the application and where sensitive data is handled.
• This helps identify potential attack paths or weak points in the design, so teams can implement appropriate security measures such as robust authentication, encryption, and input validation from the start.

Example: Reviewing how customer payment data flows through an online store can reveal risks of tampering or data leakage.

Development Phase: Code and Dependency Reviews

• During coding, developers and security teams review the application’s source code to catch insecure coding patterns, logic errors, or inadequate error handling before they reach testing environments.
• The application’s use of external components such as open-source libraries or third-party packages is examined to ensure they do not contain known vulnerabilities or incompatible licenses.
• Incorporating these checks into day-to-day development allows teams to detect and remediate vulnerabilities early, saving time and reducing the cost of fixing problems later.

Example: Identifying improper input validation that could allow attackers to manipulate database queries.

Testing Phase: Security Assessments During QA

• Once the application is built and deployed in testing or staging environments, security assessments simulate attacks against the running application to find vulnerabilities that can only be seen during execution.
• These assessments explore vulnerabilities like weak authentication, poor session management, and misconfigurations, as well as vulnerabilities introduced through complex user interactions or application logic.
• Security evaluations during this phase help ensure that vulnerabilities are addressed before the application goes live.

Example: Detecting that a login page does not enforce proper password complexity or lockouts, leaving it open to brute-force attacks.

Production Phase: Ongoing Security Monitoring and Expert Reviews

• After the application is deployed to production, it remains exposed to evolving threats. Security teams perform regular evaluations of the live environment, checking for new vulnerabilities introduced by code changes, infrastructure updates, or newly discovered vulnerabilities in components.
• Continuous monitoring is used to detect suspicious activity or exploit attempts, providing alerts or blocking attacks before they cause harm.
• Periodic manual security reviews by experts are critical to identify sophisticated vulnerabilities such as business logic vulnerabilities or multi-step attack chains that automated checks might miss.

Example: Regularly reviewing new code deployments to ensure updates have not inadvertently introduced security gaps.

Why Integrate Security Throughout the SDLC?

Embedding security assessments into every stage of development helps organizations:

• Catch vulnerabilities early, before they become expensive or damaging.
• Reduce risks from insecure design, coding errors, misconfigurations, and emerging threats.
• Maintain compliance with industry standards by ensuring security is consistently addressed.

A holistic, proactive approach to AST allows organizations to build and maintain applications that are secure by design, not just patched as an afterthought.

Want to take the next step? Learn how to choose the right application security testing toolto match your application security needs and streamline your remediation efforts.

Indusface WAS: A Comprehensive Application Security Testing Tool

While understanding application security testing is crucial, choosing the right tool makes all the difference in effectively protecting your applications. Indusface WAS is a powerful application security testing solution that combines automated vulnerability scanning with expert manual assessments offering organizations a unique, hybrid approach to AST.

Key capabilities of Indusface WAS include:

Comprehensive Vulnerability Detection: Identifies a wide range of vulnerabilities, including OWASP Top 10 risks, server misconfigurations, and business logic vulnerabilities.

Asset Discovery & Inventory: Automatically discovers web applications, APIs, and associated assets across your infrastructure. By continuously mapping your attack surface, it ensures all exposed assets — including newly deployed or forgotten apps — are identified and monitored, providing complete visibility and eliminating blind spots.

API Scanning: Covers modern applications by scanning RESTful APIs and microservices, identifying vulnerabilities like broken object-level authorization, excessive data exposure, and insecure endpoints.

AI-Crawler for Enhanced Coverage: Uses an advanced AI-powered crawler that intelligently groups UI elements based on insights from previous crawls. By reducing redundant actions and improving efficiency, it reaches areas of applications that traditional scanners often miss, significantly expanding scan coverage and delivering deeper, more accurate security assessments.

Continuous Scanning: Supports scheduled or on-demand scans to keep up with fast-moving DevOps pipelines, ensuring new vulnerabilities are identified promptly.

Zero-Day Vulnerability Identification: Features an AI-driven platform that continuously monitors diverse threat intelligence feeds. It filters and prioritizes vulnerabilities relevant to your applications, checks for proof-of-concept exploits, and evaluates the potential impact and spread. This proactive detection enables organizations to act quickly on critical zero-day vulnerabilities, enhancing security posture and operational efficiency.

No Prioritization, Instant Patching: While Indusface WAS enables precise risk prioritization by considering exploitability, business context, and potential impact not just severity scores, it goes further by offering integrated instant virtual patching on AppTrana WAAP. This means organizations do not just identify and prioritize vulnerabilities; they can immediately protect applications against open vulnerabilities, significantly reducing exposure time and risk while permanent fixes are developed.

Zero Vulnerability Reporting: Provides comprehensive reports when scans find no vulnerabilities, offering proof of security hygiene to stakeholders, customers, and compliance auditors essential for demonstrating due diligence.

Easy Integration: Works seamlessly with CI/CD pipelines and develops workflows to support shift-left security strategies without slowing releases.

Indusface WAS combines cutting-edge automation, AI insights, API scanning, and manual expert validation. It gives you complete confidence to secure your web applications and API from development through production. Stay compliant, reduce risk, and protect your business with one powerful solution.

Do not wait.  Start your free trial of Indusface WAS now and take control of your application security!